Apparatus for the electrolytic manufacture of persulphuric acid and its salts



Oct. 24, 1939. J MULLER 2,177,626

APPARATUS FOR THE ELECTROLYTIC MANUFACTURE OF PERSULPHURIC ACID AND ITS SALTS Filed Sept. 19, 1938 A TTORNEY.

Patented Oct. 24, '1939 APPARATUS FCR THE ELECTROLYTIC MAN- UFACTURE OF PERSULPHURIC ACID AND ITS SALTS Josef Miiller, Weissenstein-on-the-Drava, Germany, assignmto Oesterreichische Chemische Werke Gesellschait m. b. H., Vienna, Germany, a corporation of Germany Application September 19; 1938, Serial No. 230,583 In Austria May 21, 1931 2 Claims.

Object of my invention is a process for the manufacture of persulphuric acid and its salts by means of electrolysis and devices or apparatus by means of which such a process can be effected.

It is known to carry out electrolytic processes such as, for instance, themanufacture of persulphuric acid and its salts by means of electrolysis in devices consisting in a combination of a number of cells which are assembled into an apparatus resembling a filter press. Such a device possesses in each single cell which is divided by a diaphragm' a cathode which is formed like a chamber and through which flows the cooling water whilst the anode plate is cooled by contacting it close to the cathode of the neighbouring cell.

My invention solves the problem of cooling more eflica'ciously the anodes by means of electrolytic cells which are assembled and combined in a filter pfess like manner by providing that the liquid'cooling the cathode comes into immediate contact with the anode of the adjacent cell. Accordingly the process of my invention 1 for the electrolytic manufacture of persulphuric acid and persalts in electrolytic cells which are combined in a filter press like fashion consists substantially therein that the cooling liquid flows through a cavity or hollow space which is formed, on the one hand, by. the anode of one cell and, on the other hand, by the cathode of ever, may also as an example have the form of chambers in which case according tomy invention the wall which is nearest to the anode of the next cell is provided with perforations in order toallow the cooling liquid to come into immediate contact, with a part .ofthe anode surface' According to a special form of carrying out my' invention the single cells are not placed horizontally one next to the other but are arranged one on top of the other. Hereby the liquid, for instance, the electrolyte i. e. the anolyte or catholyte are permitted to flow through the device. by means of its gravity. I

The electrolyser may according to the process of electrolysis employed be composed of cells with manner.

.dia'iphragmcr of cells withoutdiaphragms. The

electrodes may be connected up in a bi-polar In spite of the fact that cathode and anode touch each other only to a limited extent the current passes from the cathode to the anode without any hinderance. If it is desired to carry through the electrolysis by means of electrodes connected in series the passage of the current between cathode and anode of the neighbouring cell is prevented by insulating the two.

In consequence of the more efllcacious cooling of the anodes my invention permits the increase of the yield. So, for instance, in an equipment which is composed of three cells 30 to 35% solutions of persulphuric acid may be obtained with a current yield of 80%. In the same way a considerable increase of the yield is attained when persalt solutions are prepared such as, for'instance, ammonium persulphate.

The accompanying drawing illustrates in a schematic manner various ways in which my invention may be carried into effect but I do not want to be restricted to these particular manners.

Figure 1 shows a single series of cells without diaphragm. The cathodes which have the shape of dishes and therefore are open toward one side are indicated by I. They may be made of lead or graphite. The open side of the dish is covered by a thin anode sheet consisting, for instance-of platinum. This anode sheet forms the anode ofthe adjacent cell. The cooling water passes through the' hollow spaces 3 formed by the cathode l and the anode 2. It is introduced or drained away respectively by the pipes W1, W2, W3, W4, W5, W6 or W'i, W's, W's, W4, W's, W's. The cathode couples and the anode couples are multiplied in a similar way and the intermediate spaces which form the spaces for the electrolysis are formed with the aid of insulating rings 5 such as, for instance, earthen ware rings. Within these electrolysing spaces the conduction of the current is effected by the electrolyte which enters the spaces 4 by the pipes E1 to Es and leaves them by pipes E'i to E's. The cross section of the cells can be chosen as desired; preferably I use cells of circular cross section. The connection of the liquid within the cells is effected in such a tively are screwed together tightly into a device resembling a'iilter press. These screws are not shown in the drawing. Figure 2 shows a device of substantially the same construction as Figure 1 with the difference that the cells are constructed as diaphragm cells. The diaphragms .8 are clamped in between the insulating frames 1 and 8. The anolyte and the catholyte are introduced into the anode spaces 9 or cathode spaces H) respectively formed by means of the diaphragms. The cells may be arranged in this case in series as regards the conduct of the liquid in such a waythat the anolyte flows through all the anode spaces and the catholyte through all the cathode spaces, or according to Figure 2 they may be provided with separate inlets and outlets for the anolyte and the catholyte. The Figures 3 and 4 show a manner of carrying out the device in the form of an upright apparatus. In order to make sure that the horizontally arranged electrodes are properly and completely covered with the liquid and completely wetted by it, it is necessary that the level of the liquid is at least in the same plane withthe surface of the electrodes or on a higher plane. As shown in Figures 3 and 4 this is attained by a corresponding formation of the upper electrode namely by providing' that these are shaped with a cavity or a depression. In the Figures 3 and 4 the cathodes l are shown with such depressions or recesses. Hereby collecting rooms II are formed for taking up the liberated gases. The connection of the cells as regards the conduct of the liquid is in the upright just as simple as in the horizontally situated arrangement according to Figures 1 and 2, and has the advantage that the liquid is run through by gravity. In order to make the whole device clear simple andeasily accessible the islets W1, W2 and so forth and the outlets Wi, W2

and so forth for the cooling liquor are arranged in reverse order in respect to those for the electrolyte (E1, E2 and so forth or E1, E'2 and so forth). The outlets for'the cooling water are taken right up to just below the anode surfaces in order to make certainthat the anodes are properly in contact with the cooling, water.

According to Figure 4 the cathode l is given the shape of a chamber, the one wall of which adjacent to anode 2 is provided with openings or perforations l2. The diaphragm 6 has the form of a more or less rectangular dish.

-When the cells are arranged in an upright position according to Figures 3 and 4 the insulating rings may be provided with openings, for instance, of a circular shape which are situated above the overflows of the electrolyte. In this way the cathodes and even the diaphragms are made accessible. In this latter case the cells need not be closed.

What I claim is: 1. A unitary electrolytic cell assembly of the bipolar type for the preparation of persulphuric acid and persalts which comprises a plurality of fluid-cooled individual electrolytic cells arranged one above the other in a vertically extending fllter-press-like arrangement, each of said electrolytic cells comprising a cathode, an anode, and

a porous diaphragm positioned between said cathode and said anode in each individual electrolytic cell to form a space adjacent said cathode containing acatholyte and a space adjacent said anode containing an anolyte, said cathodes being formed with an interior chamber for cooling fluid, said anodes being positioned in juxtaposition to the cathode of an adjacent individual electrolytic cell in such a manner as to form a closure at one side of the interior chamber in said cathode whereby both said anode and said cathode are cooled by direct contact with cooling fluid present in said chamber in said cathode, and fluid conducting means between adjoining cells for passing the catholyte and anolyte by gravity from each cell to the cathode and anode spaces respectively of the next lower cell in said unitary assembly.

2; A unitary electrolytic cell assembly of the bipolar type for the preparation of persulphuric acid and persalts which comprises a plurality of fluid cooled individual electrolytic cells arranged one above the other in a vertically extending filter-press-like arrangement, each of said electrolytic cells comprising a cathode, an anode, and a porous diaphragm positioned between said cathode and said anodein each individual electrolytic cell to form a space adjacent said cathode containing catholyte and a space adjacent said anode containing an anolyte, said cathodes being formed with an interior chamber for cooling fluid and being provided with one wall whichis anodes directly through said perforated wall, said anodes being positioned in juxtaposition to said perforated wall of the cathode of an adjacent .individual electrolytic cell in such a manner as to form a closure at one side of the interiorchamber in said cathode, whereby both said cathode and anode are cooled by direct contact with cooling fluid present in said chamber in said cathode, and means for passing the catholyte and anolyte from each individual electrolytic cell to the spaces adjacent the cathode and anode respectively of the next lower individual electrolytic cell of said unitary assembly.

aosmn MULLER.

.- ,40 perforated to permit cooling fluid to contact said 

